Turbochargers are commonly used to increase the power of a vehicle engine. Turbochargers include a turbine which generates pressurized air, and the air is forced into the engine to increase combustion pressure, and therefore increase the power generated by the engine.
With some tubocharging systems, a portion of the pressurized air is bled off to create a vacuum and induce the flow of purge vapor. The vacuum created is used as part of a purge system, where the purge system directs purge vapors from a fuel tank through various conduits to redirect the vapors into the intake manifold of the engine, and burn off these vapors through combustion.
Some turbo purge systems use a venturi vacuum generator (such as a vacuum pump) to allow purge of the evaporative system while the turbocharger is activated (i.e., the intake manifold is under positive pressure). In typical systems, some of the pressure created by the turbo is bled off, through a venturi, which creates the vacuum needed in the venturi to induce purge vapor flow. These venturi nozzles typically are connected to the air intake box through the use of a hose, through which flows the turbo bleed flow, and the hydrocarbon rich, purge vapor. If this hose becomes detached from the air intake box, this could result in blowing hydrocarbons into the atmosphere under the hood of the car.
There are a number of systems currently in production that are potentially non-compliance in terms of having the ability to be able to detect a hose-off condition. Attempts have been made to address this issue by putting the entire vacuum generating venturi into the air box. Other solutions have included adding pressure transducers to the line. Both of these approaches involve additional cost, and may not completely solve the problem.
Accordingly, there exists a need for the prevention of the release of hydrocarbon rich purge vapor in an air flow system when one of the hoses becomes disconnected.